The present invention relates generally to the field of data security, and more specifically to a method of rendering the data unusable in a storage device in the absence of a proper security key.
Known methods of protecting data from unauthorized access include the use of various forms of encryption by which the data is transformed into an unusable form. Upon reception of a correct (valid) security key, the data is transformed back into its original form whereupon it is again usable. Encryption is performed by software and/or hardware. In some implementations, data is encrypted/decrypted “on the fly” as it is stored and/or retrieved from a storage medium such as a hard disk.
A storage device, such as a USB flash drive, has many addressable storage locations (blocks). The storage is managed and organized by a file system. For example, an 8-gigabyte drive, may have at least two million 4-kilobyte blocks in its address space. A 1-megabyte file, for example, would occupy at least 250 (4-kilobyte) blocks, scattered throughout the two million blocks. The file system keeps track of all 250 blocks of storage associated with the file (as well as any other data stored within the remainder of the two million blocks). This means keeping track of: (i) the addresses of all 250 blocks; and (ii) the proper sequential order in which the blocks belong in the file. A commonly used file system uses a file allocation table (FAT, sometime referred to herein as a data map) to manage and organize the storage.